Unit 4 Test Questions

Post possible questions for test on friday here. :]

1. During the process of photosynthesis:
6 CO2 (g) + 6 H2O(aq) à C6H12O6(aq) + 6 O2(g)
a) carbon dioxide is oxidized
b) hydrogen in water is reduced
c) oxygen in carbondioxide and/or water is oxidized - answer
d) oxygen in glucose is oxidized
e) carbon in glucose is oxidized

2. All galvanic and electolytic cells require:
a) an external power supply
b) a voltmeter
c) one electrode and two electrolytes
d) two electrodes and one electrolyte - answer
e) a porous barrier

3. How long does it take to produce 4.50g of scandium metal in the electrolysis of molten scandium chloride using a current of 8.5 A:
a) 57 min - answer
b) 19 min
c) 6.3 min
d) 1.1 min
e) 0.54 min

4. When balancing a redox reaction in a basic solution, one must:
a) Add H ions to both sides of the reaction
b) Add OH ions to both sides of the reaction - answer
c) Add water to both sides of the reaction
d) Add H to one of the reaction
e) Add OH to one side of the reaction

5. Select the statement which is correct.
a) Oxidation is the loss of electrons and a rise in oxidation number - answer
b) Reduction is the gain of electrons and a rise oxidation number
c) Oxidation is the gain of electrons and a lowered oxidation number
d) Reduction is the loss of electrons and a lowered oxidation number

6. Whose experiments with a dead frog led to incorrect conclusions?
a) Volta
b) Daniell
c) Farraday
d) Galvani - answer
e) Nernst

7. Who was credited with the invention of the battery?
a) Volta - answer
b) Daniell
c) Farraday
d) Galvani
e) Nernst

8. What does a lower electrode potential (E naught) mean about a chemical?
a) it is a stronger reducing agent
b) it is a stronger oxidizing agent
c) it will be reduced when reacted with a chemical of higher electrode potential
d) it will be oxidized when reacted with a chemical of a higher electrode potential
e) at least two of statements are true - answer (a and d are both true)

9. Will a Galvanic cell created with Zn and Cr react spontaneously?
(yes because Zn is a strong oxidixing agent and Cr is a strong reducing agent and the cell's potential (E.naught) is more than 0)

10. What is the oxidation number oh hydrogen(excluding hydrides and Hydrogen Peroxide)?
a) -1
b) +1 <--- Correct Answer
c) -2
d) +2

11. What is the oxidation number of oxygen?
a) -1
b) +1
c) +2
d) -2 <----Correct Answer

12. What is the oxidation number of the Carbon on the reactants side in the following equation?
CH4+2O2 = CO2 + 2H2O

a) +4 <--- Wrong Answer
b) -4 <--- Right Answer
c) +1
d) -1

Isn't q.12 (-4)?
H+ has an oxidation number of (+1) and since there are 4, the charge is (+4). Since the overall charge is (0), then Carbon has to be (-4) right? On the product side of the equation (+4) would be right though.

13. In an electrolytic cell which of the following is the negative electrode?
a) anode
b) cathode <--- Correct Answer
c) none of the above
d) circumlocution